P0300 random misfire code HELP!
 

Hey guys heres the story, I got a p0300 code last fall, cleared it w my friends computer and it came back a few weeks later. I stored it for the winter, code was still there when I put it back on the road the other day. I scheduled a dealer service for today and of course the light went off 2 mi from the dealership!! Wtf! Anyone know why this would happen?? I have a bunch of parts waiting to go on my car but I want this fixed first so I dont have to worry bout voiding the warranty. Thanks.

It happened to my car after sitting for the Winter. I think the fuel trims were all messed up after sitting for so long, but once it was idling for a while it seemed fine so I just reset the code and it hasn't come back.

Is your car still stock?

Still stock. I was getting the code before I took it off the road. Had it for a few weeks back in the fall, cleared it and it came back. I drove it for a few more weeks w it on before it went off the road for the winter.

It is possible the AF ratios are a little bit out of whack. I've seen this happen a couple of times even on stock cars.

But first make sure you're using good quality gas, the 370Z is pretty picky and throws a tizzy if you give it the cheap stuff.

:iagree:

Well hopefully thats it. What really confuses me is the fact that it was on for so long then went off. I was almost on empty when I gassed it up yesterday and the light went off today which makes it seem like it could be a fuel issue. But, I filled it up plenty of times when the light was on last fall and it never went off then.

The light goes off when it hasn't seen a misfire for a given number of cycles and time. If they continue to occur sporadically then the code stays active.

It can also be caused by the primary O2 sensors giving bad feedback data, but this mainly occurs in high mileage vehicles.

I was wondering yesterday about the cycles. How long does it take to run completely through a cycle on a 370? Btw thanks for the help rep^.

I'm not sure of their exact formula, but they usually stick for about 3-4 starts and/or 30-50 miles.

I also got the same code shortly after nearly stalling while on a steep hill. Cleared the code and hasn't happened again.

My biggest concern is the fact that I have cleared it and it returned. I really wanted to feel comfortable about the running condition before I screw up my warranty by putting my Stillen CBE & Gen 3 on. Gonna have to say to hell with it though, I cant look at these parts any longer, they have been here for months. Installing myself saturday :) Cant wait to hear her new growl.

MIL is on and Just diagnosed mine today. P0300. going to reset, run out this tank of gas, and make sure i refill on quality gas and see how it goes. Will keep posted.

any update? after parking my car for 1 week the check engine light is on due to misfire. took it to dealer and they said might be low voltage??